This invention relates to the gettering of hydrogen. More particularly, this invention relates to the provision of a hydrogen getter material on a surface of packing material such as a foam pad to provide both mechanical support and protection against hydrogen gas for hydrogen sensitive apparatus positioned and mechanically supported in a container by the foam pad.
The accumulation of hydrogen in a confined space such as a hermetically sealed container is undesirable. When the sealed container contains exposed electronics, any hydrogen present in the container, for example, from an improperly cured potting material, may have a deleterious effect on the exposed electronics. The present of hydrogen may also constitute an explosion hazard or a source of corrosion for heavy metals also contained in the sealed container.
It is well known in the art that hydrogen may be removed from a container using materials known as getters that either absorb or react with hydrogen. For example, Anderson et al. U.S. Pat. No. 3,896,042 (and its division Anderson et al. U.S. Pat. No. 3,963,826) discloses the formation of a hydrogen getter by coating a hydrogenation catalyst such as platinum or palladium with an active unsaturated organic material. Harrah et al. U.S. Pat. No. 4,405,487 describes a combination moisture and hydrogen getter composition comprising a moisture getter such as an oxidizable metal, and a hydrogen getter comprising a solid acetylenic compound and a hydrogenation catalyst. Shepodd et al. U.S. Pat. Nos. 5,624,598 and 5,703,378 describe hydrogen gettering compositions comprising organic compounds containing double or triple bonds and a hydrogenation catalyst for catalyzing the reaction between the organic compound and hydrogen, while Shepodd et al. U.S. Pat. No. 5,837,158 discloses a hydrogen gettering composition comprising organic polymers having carbon-carbon double bonds throughout the structure, a noble metal hydrogenation catalyst such as a platinum or palladium catalyst, and an inert catalyst support material such as carbon.
While such getter compositions are capable of removing undesirable hydrogen from a sealed container, there are problems associated with the use of such getters. For example, the physical disposition of the getter material within the sealed container may be as a loose solid, pressed pellets, or as a coating applied to interior surfaces of the sealed container. If the getter material is present as a loose solid, its presence and mobility may interfere with the operation of the contents of the sealed container, and the ability of the loose getter material to shift positions in the sealed container may interfere with a desired uniformity or homogeneity of the distribution of the getter material throughout the volume of the sealed container. If the getter material is present as pressed pellets, it may not be possible to place it in close proximity to the hydrogen source. On the other hand, if the getter is applied as a coating to an interior surface of the sealed container, the problem of uniformity of distribution is solved, but the adherence of the coating material to the surface of the container may be less than satisfactory depending upon the type of material constituting the sealed container. Furthermore, removal of the coating material from the surfaces of the container, for example, to permit replacement, or analysis of the getter material for its efficacy in removal of hydrogen, may be difficult when the getter material has been applied to the container surfaces, for example, as a coating.
Sealed containers containing apparatus are also conventionally provided with packing materials which serve to prevent or inhibit movement of the apparatus within the sealed container to thereby reduce problems of breakage or other damage to the apparatus within the sealed container. While such packing materials are advantageously chosen to have low, if any, emission of hydrogen, their presence in the sealed container may further impede the uniform positioning or locating of hydrogen gettering material within the sealed container.
It would, therefore, be desirable to provide a sealed container with a hydrogen gettering system wherein the hydrogen getter material is capable of being maintained uniformly distributed throughout the sealed container with movement of the getter material within the sealed container restrained, and capable of being placed in close proximity to the hydrogen source, while still permitting easy removal of the getter material from the container when desired.